Andrea
A Natural Rearing dog breeder of 30 years that I know, had one of her dogs, a 6 year old who has NEVER received a rabies vaccine titred for rabies two years ago. This dog had sufficient rabies antibodies inherited from maternal antibodies. There are other dogs in this exact situation. She wrote to Dr Schultz to make him aware of this and sent him a sample of blood.
I had my human homeopath order lyssin for me to give to my 3 y.o. dog (you can't buy it in health food stores here) when/if I do vaccinate him for rabies for the first time, only AFTER a rabies titre, just in case he may already have antibodies.